Jaundice is fairly common among newborn infants, and is presumably a consequence of metabolic and physiological adjustments after birth. Often, the jaundice disappears within a fairly short period of time. In many cases the jaundice is detected early and treated effectively thus curing the infant within a fairly short period of time. When an infant is jaundiced the serum bilirubin normally rises to a high level. In extreme cases, a brain-damaging condition known as kernicterus can occur, leading to significant lifelong disability. In other extreme cases the jaundice can progress severely and even lead to death. Jaundice is usually diagnosed by an invasive blood test in which blood sample is usually taken from the heel. While this blood test is considered to be safe, obtaining the blood sample is an uncomfortable invasive procedure for a newborn infant.
U.S. Pat. No. 4,267,844 by Yamanishi relates to an electro-optical medical instrument provided for measuring non-invasively the presence of bilirubin in skin tissue. The instrument in this publication utilizes a source of flash light and optical means to provide a beam of light to illuminate the skin tissue. A portion of the reflected light is collected and separated by optical means to two components: One, having a central wavelength of 455 nm, which is known as being highly absorbed by bilirubin in skin tissue; And another having a wavelength greater than 500 nm, which absorption by the bilirubin in the skin tissue is low. These optical signals are measured by photoelectric transducers, the electrical output of which is amplified, and then used to compute a bilirubin indication by means of a logarithmic converter. User obtained calibration is called upon to convert the bilirubin indication to serum bilirubin concentration.
U.S. Pat. No. 6,064,898 by Aldrich relates to a non-invasive blood component analyzer using spectrophotometry. The analyzer in this publication utilizes measurements of transmitted light having various wavelengths selected in accordance with the blood components of interest. The parameters used to derive the blood components are each given by the difference between the systolic and diastolic values of the relevant measured signal. The visible wavelengths mentioned are 420 nm, 548 nm, 506 nm, 521 nm, 569 nm, and 586 nm. The first two are proposed for the measurement of bilirubin concentration in skin tissue.
Another non-invasive bilirubin measuring instrument is described in U.S. Pat. No. 5,792,049, by Eppstein, in which the reflectance of skin tissue is measured at several visible and near infra-red wavelengths. The measured values of reflectance are utilized to arrive at an estimate of the serum bilirubin concentration. For calibrating the instrument, the reflectance of a calibration target is measured at these same wavelengths
It is an object of the present invention to provide a method and means for applying non-invasive measurements for detecting the bilirubin level in a subject. It is a further object of the present invention to provide a method and means for applying non-invasive measurements for detecting the bilirubin level in a subject in a fast and simple manner.
Other objects and advantages of the present invention will become apparent as the description proceeds.
It is noted that the embodiments exemplified in the figures are not intended to be in scale and are in diagram form to facilitate ease of understanding and description.